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From: Nick Piggin <npiggin@suse.de>
To: Albert Herranz <albert_herranz@yahoo.es>,
	aya Kumar <jayakumar.lkml@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-mm@kvack.org
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: page_mkwrite vs pte dirty race in fb_defio
Date: Wed, 26 May 2010 02:01:49 +1000	[thread overview]
Message-ID: <20100525160149.GE20853@laptop> (raw)

Hi,

I couldn't find where this patch (49bbd815fd8) was discussed, so I'll
make my own thread. Adding a few lists to cc because it might be of
interest to driver and filesystem writers.

The old ->page_mkwrite calling convention was causing problems exactly
because of this race, and we solved it by allowing page_mkwrite to
return with the page locked, and the lock will be held until the
pte is marked dirty. See commit b827e496c893de0c0f142abfaeb8730a2fd6b37f.

I hope that should provide a more elegant solution to your problem. I
would really like you to take a look at that, because we already have
filesystem code (NFS) relying on it, and more code we have relying on
this synchronization, the more chance we would find a subtle problem
with it (also it should be just nicer).

Thanks,
Nick


WARNING: multiple messages have this Message-ID (diff)
From: Nick Piggin <npiggin@suse.de>
To: Albert Herranz <albert_herranz@yahoo.es>,
	aya Kumar <jayakumar.lkml@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-mm@kvack.org
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: page_mkwrite vs pte dirty race in fb_defio
Date: Wed, 26 May 2010 02:01:49 +1000	[thread overview]
Message-ID: <20100525160149.GE20853@laptop> (raw)

Hi,

I couldn't find where this patch (49bbd815fd8) was discussed, so I'll
make my own thread. Adding a few lists to cc because it might be of
interest to driver and filesystem writers.

The old ->page_mkwrite calling convention was causing problems exactly
because of this race, and we solved it by allowing page_mkwrite to
return with the page locked, and the lock will be held until the
pte is marked dirty. See commit b827e496c893de0c0f142abfaeb8730a2fd6b37f.

I hope that should provide a more elegant solution to your problem. I
would really like you to take a look at that, because we already have
filesystem code (NFS) relying on it, and more code we have relying on
this synchronization, the more chance we would find a subtle problem
with it (also it should be just nicer).

Thanks,
Nick

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             reply	other threads:[~2010-05-25 16:01 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-25 16:01 Nick Piggin [this message]
2010-05-25 16:01 ` page_mkwrite vs pte dirty race in fb_defio Nick Piggin
2010-05-25 18:26 ` Albert Herranz
2010-05-25 18:26   ` Albert Herranz
2010-05-25 18:26   ` Albert Herranz
2010-05-25 18:47   ` Nick Piggin
2010-05-25 18:47     ` Nick Piggin
2010-05-25 18:47     ` Nick Piggin
2010-05-25 22:13     ` [Bulk] " Albert Herranz
2010-05-25 22:13       ` Albert Herranz
2010-05-25 22:13       ` Albert Herranz

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